The present invention relates in general to battery charging and more particularly concerns an improved battery charging circuit with silicon controlled rectifiers triggered by a pedestal and cosine modified ramp (PCMR) unijunction circuit that may charge a dead battery while limiting the initial surge current and providing short circuit protection, properly establishing a trickle charge when the battery is charged to maintain the float potential and limiting the average charging current when the battery impedance is low and/or line conditions are high with reliable circuitry that is relatively inexpensive.
The present invention is an improvement over the invention disclosed in U.S. Pat. No. 3,766,463.
It is an important object of this invention to provide improved battery charging circuitry.
It is a further object of the invention to achieve the preceding object with a circuit capable of charging a battery while limiting the initial surge current delivered to the battery and providing short circuit protection.
It is another object of the invention to achieve one or more of the preceding objects while limiting the current delivered to a fully charged battery to a level required to maintain float potential.
It is a further object of the invention to achieve one or more of the preceding objects while limiting the average value of current delivered to the battery during low battery impedance and/or high line conditions.
It is a further object of the invention to achieve one or more of the preceding objects with reliable circuitry that is relatively inexpensive to fabricate and relatively easy to adjust and capable of maintaining a battery, such an as emergency battery, at float potential for long periods of time and rapidly restoring the battery to float level when the battery is discharged.